My problem with this plot is:

four year old girl

I wrote maybe two weeks ago about children? Semi-recently about behavior in association to age. So lemme explain my issue.

A typical "four year old" on the cognitive development scale is going to be able to group things correctly, rapid language development, basic reasoning skills, but predominantly they are in a phase where make believe/imaginative play gets really intense, complex and lasts for a long period of time. Chatty kids ask non-stop questions. "Why are we eating peas? Peas are good for you. Why are peas good for you? Because peas are x, y, and z." Etc.

Ages ago, I had a nephew at 5 who asked me: "What are those things are your teeth, Auntie Terra?" And I got into a twenty minute long explanation with questions on what braces are, how they function, how they got on my teeth, etc. Then right after that finished, my nephew promptly went up to his mother and grandmother and declared that Auntie Terra had strange things on her teeth and then made up information that wasn't really right per se. /was not work the effort on my part

My point being an average "four year old" being released into a village and then manipulated into delivering products and still being capable of staying on task and not completely lost in this village, which from your description isn't small. And at this age, it's just really pushes into not believe-able that a kid could remain that focused and on point, AND that adults would trust a small fry like that.

So I would age up to a seven year old girl, or maybe a "mature" six year old in the sense that mom has been slowly getting worse over time, so by six she's learning to take care of mom for little stuff, so this is just another logical step.

Now, scenario #1 makes sense for a 6/7. Scenario #2 needs a more developed child so I would go 7/8.

For comparison's sake, if you have read GRRM's work, in the beginning, Sansa is 11, Arya is 9, and Bran is 7.